The primary objective of this study is to evaluate whether adult, insulin-dependent diabetics experience higher rates of cognitive impairment than non-diabetic matched controls. Overall cognitive functioning and a broad range of specific cognitive functions will be compared between diabetic and nondiabetic groups. Relative severity and patterns of impairment found frequently among the diabetics will also be identified. Secondly, within th diabetic group, analyses will be conducted to suggest potential risk factors for further study. Associations will be examined between impairment and sociodemographic, medical, and psychiatric factors. Measures include age, sex, duration and age at onset of diabetics, insulin regimen, diabetes education, glycosolated hemoglobin, fluctuations in blood glucose during assessment, compliance and depression. The results of these analyses will be used to plan further studies. Thirdly, results of the first two years will be used to develop several studies. Plans include the identification of subgroups at increased risk for cognitive impairment, the collection of longitudinal data to validate cross-sectional findings, treatment intervention studies, and attempts to develop shorter, less expensive screening tests to assess cognitive impairment among diabetics. The findings of this study and subsequent studies will be presented at scientific meetings and submitted for publication.